You can only put one type of enchantment on once, so when you have two or three enchantment slots, you have to use the other for something.
Yes, Retribution is pretty useless, both as a skill and enchantment, because it returns a percentage of the damage that is done to you to an enemy. The problem is that enemy HP is hugely inflated compared to the player's HP, and if it wasn't enough to kill you, it's not going to do much to hurt them. It adds a bit of damage, but there are better options to use first.
Jewellery's only good enchantment is Healing Aura, but that requires the supply-limited Malachite Gems, so it's not feasible to casually slap on. Just use whatever you feel like on jewellery.
